1- Login to MailChimp Account.
2- Go to list to create new list
3- go to list settings and unique ID
4-Copy list ID
5- Go to sign up form link code to get form URL
6- copy signup form URL
7- to set form redirection follow these steps:
a- From Dashboard go to design a form tab
b- Choose signup "thank you" page from drob down menu
c- insert thank you page url